On 5 November, AVO raised the Aviation Color Code for Redoubt to Yellow and the Volcano Alert Level to Advisory because of significant changes in gas emission and heat output during the previous several months. The changes were a departure from the long-observed background activity. ASTER satellite images from 13 October detected warming near the summit craters; evidence of warming had been directly observed in July 2008. Fumarolic activity and water flowing beneath Drift Glacier on the N flank had produced a 45-m-wide melt or collapse hole at an elevation of about 1,700 m (5,600 ft) on the Drift Glacier. On 2 November, a slushy debris-flow deposit originated from about the location of the 1966-68 vent. During 6-11 November, no activity was observed on satellite imagery and seismicity remained low.